Shops with an off-licence made their hours similar to those of public houses, opening during lunch hours and from early evening to the mandatory closing time, usually 22:30 or 23:00.

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How do you read "23:00"?

generally, for 24-hour clocks, we just say

23:00 as twenty-three hundred hours
22:30 is just twenty-two thirty with "hours" more often omitted
Many write 24-hour times without the colon.

if it's very early morning hours, like 0430, some say oh-dark thirty